Time for dedicated outlets!

Jea48, the bare wire is the ground. It is connected to the ground bar in the panel and at the outlet it is connected to the box and outlet ground screw

Here's a thought - if you have the space, consider a sub-panel adjacent to your rack depending on where the equipment is located from an aesthetic stand-point.

I added a dedicated 60amp sub-panel using 6-gauge in its own conduit from the main panel. That opens up the option of 240 volt power conditioners at the rack which is nice and very short runs from the panel to the outlets.

I grounded the sub-panel separate from the main panel using a grounding plate buried outside connected with 6-gauge grounding wire. Good fun.

cerberus79

#12 wire is rated for 20 amps and #10 is rated for 30 amps. If you use a 20 amp breaker it will trip at 85% of rating so what is the point of going to #10.

Derating the wire will reduce voltage drop. The calculation of the proper gauge wire for a given amperage hinges on the distance of the wire, so you can't quite say, " #12 wire is rated for 20 amps," although it is generally true.

bumperdoo

I grounded the sub-panel separate from the main panel using a grounding plate buried outside connected with 6-gauge grounding wire

That's a violation of the NEC and potentially hazardous. All grounds must be bonded together at the service panel, without exception.

The highest quality ground is a low impedance ground, and that's the ground provided by your utility. If there's an issue with your utility's ground, it's their responsibility to correct it.

Cleeds, that is true. If the run is 50 feet or more you should use # 10. If 100 ft  go to # 8.